1. Field of the Invention
This invention relates to rock drilling apparatus, and in particular to reamer and stabilizer asemblies adapted to be fitted between the bit and drill stem.
2. Prior Art
In rock drills it is customary to utilize a stabilizer reamer between the bit of the rock drill and the drill stem. With the stabilizer thus installed, the bit which normally has a tendency to wander is somewhat directionally stabilized so that drilling follows a straight course.
The stabilizer units, which are secured at one end to the bit and at one end to the drill stem, usually have three or more roller assemblies which lie on a circle having a diameter approximately the same as the drill bit so as to have a tight, yet rotatable, fit in the hole drilled by the bit. The stabilizing rollers do actually perform a reaming function in many cases as they are provided with bits or protrusions which remove certain anomolies in the drill hole caused by the action of the bit.
In those stabilizer reamers wherein more of a stabilizing, rather than reaming, function is performed, the stabilizer rolls are usually of a cylindrical nature and mounted for rotation on axles which extend parallel to the rotational axis of the bit. After much usage the roller bits quite frequently wear as do the bearings between the axles and the rollers, and it is quite often necessary to change the stabilizer rolls from time to time.
In most reamer and stabilizing units of prior art, the axles on which the rolls are mounted are usually held in place on the stabilizer body by exteriorily available screws or studs which are themselves subject to wear during an operation and, consequently, the removal and replacement of rolls becomes a work-shop rather than on-the-spot operation, and special tools are required. Consequently, unless there is a stabilizer unit immediately at hand to replace the entire worn stabilizer unit, the down time becomes excessive.